Add cname to site config (#374)
Add cname to site config (#374)

Summary:
So the `CNAME` file will automatically be published to `gh-pages`.
Pull Request resolved: https://github.com/facebook/redex/pull/374

Reviewed By: JoelMarcey

Differential Revision: D14179609

Pulled By: int3

fbshipit-source-id: 6db3b6c0b76d7bfabc9d7ce9cf29f75dff6d99d6

facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex